Mykhaylyk V, Nagorny S S, Nahorna V V, Wang P, Frogley M D, Swiderski L, Kolomiets V, Vasylechko L
Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, UK.
Arthur B. McDonald Canadian Astroparticle Physics Research Institute, Queen's University Kingston, ON, K7L 3N6, Canada.
Dalton Trans. 2022 May 3;51(17):6944-6954. doi: 10.1039/d2dt00223j.
Crystals of metal hexachlorides CsMCl (M = Hf or Zr) have recently emerged as promising materials for scintillation applications due to their excellent energy resolution. In this work, we investigated the crystal structure and scintillation properties of CsHfCl and CsZrCl crystals in the broad temperature range from 9 to 300 K. X-ray diffraction data confirmed the same cubic structure (space group ) for CsHfCl and CsZrCl over the entire examined temperature range. The room temperature scintillation light yield of CsHfCl excited with a Cs γ-source is measured to be 24 800 photons per MeV, while CsZrCl exhibits 33 900 photons per MeV resulting in energy resolutions of 5.3% and 4.5%, respectively. The alpha-to-beta ratio determined at room temperature for 5.5 MeV α-particles from an Am source is equal to 0.39 for CsHfCl and 0.35 for CsZrCl. The measurements of scintillation decay curves revealed complex kinetics due to delayed recombination processes. A tangible enhancement of the scintillation yield with heating is observed in the 125-150 K range. This effect is a manifestation of negative thermal quenching explained by thermal activation of trapped carriers. A model of the emission centre is proposed that consistently explains the observed changes of emission intensity with temperature in the crystals under study.
